Fully pivot to pirates, some UI

src/age_of_sail/core.clj

@@ -0,0 +1,83 @@
+(ns age-of-sail.core
+  (:require [age-of-sail.vec2 :refer :all]
+            [seesaw.core :refer :all]
+            [seesaw.bind :as b]
+            [clojure.math :as math]))
+
+(def tickrate 100)
+(def hardcoded-wind [0.1 3.0]) ;; A strong easternly wind!
+(defonce ships (atom []))
+(defonce program (atom nil))
+
+(defn find-ship
+  [ships name]
+  (some #(when (= name (:name @%)) %) ships))
+
+(defn downwind-force
+  "Calculates the force for a single square downwind sail
+  Force = furl × length² × dot(wind, heading)"
+  [sail wind heading]
+  (scale heading (* (:furl sail) (:length sail) (:length sail) (dot wind heading))))
+
+(defn downwind-sails-force
+  [ship wind]
+  (loop [slots (:slots ship)
+         force (zero)]
+    (if-let [slot (first slots)]
+      (if (= :downwind-sail (:type slot))
+        (recur (rest slots) (add force (downwind-force slot wind (:heading ship))))
+        (recur (rest slots) force))
+      force)))
+
+(defn physics-step
+  [ship wind]
+  (dosync
+   ;; Update position
+   (alter ship update :position add (scale (:velocity @ship) (/ tickrate)))
+   ;; linear dampening
+   (alter ship update :velocity scale (- 1.0 (/ 0.5 tickrate)))
+   ;; wind force
+   (alter ship update :velocity add (scale (downwind-sails-force @ship wind) (/ tickrate)))))
+
+(defn tick
+  [ships]
+  (doseq [ship ships]
+    (-> ship (physics-step hardcoded-wind))))
+
+(defn stop-program
+  []
+  (when @program
+    (reset! @program false)))
+
+(defn start-program
+  []
+  (stop-program)
+  (let [thread-continue (atom true)]
+    (.start
+     (Thread.
+      (fn []
+        (while @thread-continue
+          (tick @ships)
+          (Thread/sleep (quot 1000 tickrate))))))
+    (reset! program thread-continue)))
+
+;; UI
+(def tracked-ship (atom nil))
+
+(defn ship-chooser
+  []
+  (let [name (text :columns 20)]
+    (b/bind (.getDocument name) (b/transform #(find-ship @ships %)) tracked-ship)
+    (flow-panel :items ["Ship Name" name])))
+
+(defn ship-info
+  [])
+
+(defn show-ui
+  []
+  (-> (frame :title "Space Sim" :content (ship-chooser)) pack! show!))
+
+(defn -main
+  [args]
+  (start-program)
+  (show-ui))

src/age_of_sail/vec2.clj

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+(ns age-of-sail.vec2
+  (:require [clojure.math :as math]))
+
+(defn zero
+  []
+  [0. 0.])
+
+(defn add
+  [v1 v2]
+  (mapv + v1 v2))
+
+(defn scale
+  [v & scalars]
+  (mapv #(* (apply * scalars) %) v))
+
+(defn len2
+  [v]
+  (apply + (map #(* % %) v)))
+
+(defn len
+  [v]
+  (math/sqrt (len2 v)))
+
+(defn normalize
+  [v]
+  (let [length (len v)]
+    (mapv #(/ % length) v)))
+
+(defn dot
+  [v1 v2]
+  (apply + (map * v1 v2)))